usually went through to the early hours of the morning; for anybody not disposed to seek solitude and privacy, there was little else to do after work at Pithead.
The Ganymeans developed a strong partiality for scotch whiskey, which they preferred neat, by the tumblerful. They reciprocated by bringing in a distillation of their own from the
It was during one of these evenings that Hunt decided to broach directly the subject that had been puzzling more than a few of the Earthmen for some time. Shilohin was present, so was Monchar, Garuth #146;s second-in- command, together with four other Ganymeans; on the Earth side were Danchekker, Vince Carizan the electronics engineer, and a half-dozen others.
'There is a point that #146;s been bothering some of us,' he said, by that time having come to appreciate the Ganymean preference for direct speech. 'You must know that having people around today who can describe how Earth was in the distant past makes us want to ask all kinds of questions, yet you never seem to want to talk about it. Why?' A few murmurs from all around endorsed the question. The room suddenly became very quiet. The Ganymeans seemed ill at ease again and looked at each other as if hoping someone else would take the lead.
Eventually Shilohin replied. 'We know very little about your world. It #146;s a delicate issue. You have a culture and history that are completely strange. . . .' She gave the Ganymean equivalent of a shrug. 'Customs, values, manners. . . accepted ways of saying things. We wouldn #146;t want to offend somebody by unwittingly saying the wrong thing, so we tend to avoid the subject.'
Somehow the answer was not really convincing.
'We all believe there #146;s a deeper reason than that,' Hunt said candidly. 'We in this room might come from different origins, but first and foremost we are all scientists. Truth is our business and we shouldn #146;t shy away from the facts. This is an informal occasion and we all know each other pretty well now. We #146;d like you to be frank. We #146;re curious.'
The air became charged with expectancy. Shilohin looked again toward Monchar, who quietly signaled his acquiescence. She downed the last of her drink slowly as she collected her thoughts, then looked up to address the room.
'Very well. Perhaps, as you say, we would do better without any secrets. There was one crucial difference between the patterns of natural evolution that unfolded on your world and on our world #151;on Minerva there were no carnivores.' She paused as if waiting for a response, but the Earthmen continued to sit in silence; obviously there was more to come. She felt a twinge of sudden relief inside. Perhaps the Ganymeans had been overapprehensive of the possible reactions of these unpredictable and violently inclined dwarves after all.
'The basic reason for this difference, believe it or not, lay in the fact that Minerva was much farther away from the Sun.' She went on to explain. 'Life could never have developed on Minerva at all without the greenhouse effect, which you already know about. Even so, it was a cold planet, certainly in comparison to Earth.
'But this greenhouse effect kept the Minervan oceans in a liquid state and, as on Earth, life first appeared in the shallower parts of the oceans. Conditions there did not favor progression toward higher forms of life as much as on the warmer Earth; the evolutionary process was relatively slow.'
'But intelligence appeared there much earlier than it did on Earth,' somebody tossed in. 'Seems a little strange.'
'Only because Minerva was further from the Sun and cooled more quickly,' Shilohin replied. 'That meant that life got off to an early start there.'
'Okay.'
She resumed. 'The patterns of evolution on the two worlds were remarkably similar to start with. Complex proteins appeared, leading eventually to self-replicating molecules, which in time led to the formation of living cells. Unicellular forms came first, then colonies of cells and after them multicelled organisms with specialized features #151;all of them variations on the basic marine invertebrate form.
'The point of departure at which the two lines went their own way, each in response to the conditions prevailing on its own planet, was marked by the appearance of marine vertebrates #151; boned fishes. This stage marked a plateau beyond which the Minervan species couldn #146;t progress toward anything higher until they had solved a fundamental problem that was not faced by their counterparts on Earth. The problem was simply their colder environment.
'You see, as improvements appeared in the Minervan fish species, the improved body processes and more highly refined organs demanded more oxygen. But the demand was already high because of the lower temperature. The primitive circulatory systems of the early Minervan fish couldn #146;t cope with the dual workload of carrying enough oxygen to the cells, and of carrying wastes and toxins away from the cells #151;not if progress toward anything more advanced was going to be made, anyway.'
Shilohin paused again to invite questions. Her listeners were too intrigued, however, to interrupt her story at that point.
'As always happens in situations like that,' she continued, 'Nature tried a number of alternatives to find a way around the problem. The most successful experiment took the form of a secondary circulation system developing alongside the first to permit load-sharing #151;a completely duplicated network of branching ducts and vessels; thus, the primary system concentrated exclusively on circulating blood and delivering oxygen, while the secondary took over fully the job of removing the toxins.'
'How extraordinary!' Danchekker could not help exclaiming.
'Yes, I suppose that when judged by the things you #146;re used to it was, Professor.'
'One thing #151;how did the different substances find their way in and out of the right system?'
'Osmotic membranes. Do you want me to go into detail now?'
'No, er, thank you.' Danchekker held up a hand. 'That can wait until another time. Please continue.'
'Okay. Well, after this basic architecture had become sufficiently refined and established, evolution toward higher stages was able to resume once more. Mutations appeared, the environment applied selection principles, and life in the Minervan seas began diverging and specializing into many and varied species. After a while, as you would expect, a range of carnivorous types established themselves. . .'
'I thought you said there weren #146;t any,' a voice queried.
'That came later. I #146;m talking about very early times.'
'Okay.'
'Fine. So, carnivorous fish appeared on the scene and, again as you would expect, Nature immediately commenced looking for ways of protecting the victims. Now the fish that had developed the double-circulatory- system architecture, who tended to be more advanced forms anyway because of this, hit on a very efficient means of defense: the two circulatory systems became totally isolated from one another, and the concentration of toxins in the secondary system increased to lethal proportions. In other words, they became poisonous. The isolation of the secondary system from the primary prevented poison from entering the bloodstream. That would have been fatal for the owner itself, naturally.'
Carizan was frowning about something. He caught her eye and gestured for her to hold the conversation there a moment.
'Can #146;t really say I see that as being much protection at all,' he said. 'What #146;s the good in poisoning a carnivore after it #146;s eaten you? That #146;d be too late, wouldn #146;t it?'
'To the individual who was unfortunate enough to encounter one that hadn #146;t learned yet, yes,' she agreed. 'But don #146;t forget that Nature can afford to be very wasteful when it comes to individuals; it #146;s the preservation of the species as a whole that matters. When you think about it, the survival or extermination of a species can depend on whether or not a strain of predators becomes established that has a preference for them as a diet. In the situation I #146;ve described, it was impossible for such a strain of predators to emerge; if a mutation appeared that had a tendency in that direction, it would promptly destroy itself the first time it experimented in following its instinct. It would never get a chance to pass its characteristic on to any descendants, so the characteristic could never be reinforced in later generations.'
'Another thing too,' one of the UNSA biologists interjected. 'Young animals tend to imitate the feeding habits of their parents, on Earth anyway. If that was true on Minerva too, the young that managed to get born would naturally tend to pick up the habits of parents that avoided the poisonous species. It would have to be that way
